#include <iostream>
#include <cmath>
#include <cstdio>
using namespace std;
double f(double x,int n)
{
	if( n == 1)
	return sqrt( 1 + x);
	else
	return sqrt( n + f( x ,n - 1));
	
}
int main()
{
	double x;
	int n;
	cin >> x >> n;
	double r = f(x,n);
	printf("%.2f\n",r);
	
	return 0;
 } 
